Serratus Anterior Paralysis

Video courtesy of 3D Anatomy Lyon

Overview

Dr. Kevin Wall provides specialized evaluation and treatment for serratus anterior paralysis to relieve focal pain and restore scapular stability for patients in Richmond, VA, and the surrounding Central Virginia communities. The serratus anterior one of the primary stabilizers of the shoulder blade. Known as the "boxer’s muscle," it pulls the scapula forward to keep it flat against the ribs to create a stable platform for the arm (see the above video). Paralysis of this muscle is almost always caused by injury to the long thoracic nerve. When this nerve is stunned or severed, the muscle shuts down. Without its anchor, the bottom of the shoulder blade (inferior angle) lifts off the chest wall. This is one form of structural STAM, along with bone and joint problems and trapezius paralysis. Serratus anterior paralysis de-stabilizes the entire arm; patients often feel like they have no strength to lift heavy objects or punch forward.

It is paramount that a true serratus anterior paralysis is differentiated from a functional STAM, when the muscle can be profoundly hypoactive but is still capable of reactivating. Failure to recognize a functional problem could result in significant overtreatment with one of the below, invasive surgeries. Dr. Wall has extensive fellowship level training in being able to correctly evalute these conditions and ensure the right diagnosis is made and the right treatment is offered.

Symptoms

  • Medial Winging: The bottom of the blade sticks out aggressively, especially when doing pushups or pushing against a wall.

  • Weakness: Difficulty with forward elevation (lifting the arm in front of you) or pushing open a heavy door.

  • Fatigue: A deep, burning ache in the trapezius muscles as they try to compensate for the failed serratus.

Causes

  • Parsonage-Turner Syndrome: A viral/inflammatory attack on the nerve plexus (Neuralgic Amyotrophy).

  • Traction Injury: A fall or athletic collision where the neck and shoulder are stretched apart.

  • Compression: Heavy backpacks or surgical positioning.

Non-Operative Management

  • Observation: Nerves heal very slowly. We typically wait at least 6-12 months for spontaneous recovery.

  • Scapular Stabilization Brace: A custom brace can be considered manually compress the scapula to the ribs.

  • Avoidance: Avoiding the specific motion that stretches the nerve.

When is Surgery Needed?

  • Permanent Paralysis: If EMG studies show no nerve recovery after 12 months.

  • Functional Disability: If the patient cannot perform their job or daily tasks due to the loss of pushing power.

Surgical Solutions

  • Pectoralis Major to Scapula Transfer: A muscle transfer procedure that takes a portion of the large chest muscle, the pectoralis major, and routes it under the armpit to the scapula to recreate the function that the serratus anterior would typically perform.

  • Scapulothoracic Fusion: When the above transfer fails, or in patients who outright prefer it, a scapulothoracic fusion can be considered. This invasive procedure involves fusing the scapula to the ribs in the correct position so that it can no longer move abnormally and wing out.